Chiff circuit

ABSTRACT

An electronic organ provides chiff tone components at the onset of each steady tone by making use of the same signal gate for the chiff component of a relatively low-pitched tone as the steady component of a relatively high-pitched tone and, additionally, utilizes each gate to control more than one &#39;&#39;&#39;&#39;footage.&#39;&#39;&#39;&#39; Actuation of a key applies a steady gating voltage to one signal gate and a chiff pulse of gating voltage to another signal gate. For multiple footage operation, an electronic switch is arranged to be selectively keyed by plural key switches representing different footages. A footage selector switch selectively permits and prevents different footage key switches from keying the electronic switch. The signal gates and isolation circuitry between signal gates are disclosed in a variety of alternative embodiments.

United States Patent [72] Inventor Mlchoellhlhrrla 3,291,886 l2/l966 Tinker 84/l.0l Hayward, Calif. 3,333,042 7/ 1967 Brombaugh 84/l.24 [21] P 25384 Primary Examiner-D. F. Duggan [22] Filed Apr. 6, 1970 Assistant Examiner-Ulysses Weldon [45] Patented Arrame s\V H Breuni and Hurvitz and Rose 73 Assignee 0.11. Baldwin y g Cincinnati, Ohio ABSTRACT: An electronic organ provides chifl' tone components at the onset of each steady tone by making use of the [54] 8 same signal gate for the chilf component of a relatively lowpitched tone as the steady component of a relatively high- [52] U.S.Cl 84/1-24, pitched tone and, additionally, utilizes each gate to control 84/113, 84/l .26 more than one footage." Actuation of a key applies a steady [51] lnt.Cl G0lh 1/04 gating voltage to one signal gate and a chill" pulse of gating [50] Field 0! Search 84/1 .0 l voltage to another signal gate. For multiple footage operation,

1.24, 1.26, 1.13; 307/253 an electronic switch is arranged to be selectively keyed by plural key switches representing different footages. A footage [56] nd'nnm cued selector switch selectively permits and prevents different UNITED STATES PATENTS footage key switches from keying the electronic switch. The 2,486,208 10/1949 1116mm 84/126 signal sales and isolation circuitry between signal sales are 3,037,413 6/1962 Markowitz 84/1.24 disclosed in a variety of alternative embodiments- F KC 2a 29 w )5 ,KEYER I PATENTEUIJEB 14ml SHEET 1 BF 4 31.6.1 (PRIOR QRT) --L-4--- Z A I I I l I i 5 1 1 4 HME INVENTOR MlCHHEL R HRRRIS 2 N lll l l Ill T ATTORNEYS cum cracurr BACKGROUND OF THE INVENTION Rienstra in U.S. Pat. No. 2,486,208 recognized the importance of chiff (starting transients) in electronically simulating the tones of pipe organs. Markowitz in U.S. Pat. No. 3,037,413 disclosed a simple chiff system for the keyed-on" oscillator type of electronic organ. In U.S. Pat. No. 3,291,886 Tinker disclosed how a system similar to that of Markowitz could be achieved without resorting to diodes and how the Markowitz teaching could be applied to continuously running oscillator-type organs. The present invention is an improvement on Brombaughs gated continuous oscillator system, disclosed in U.S. Pat. No. 3,333,042. Although Brombaugh discloses how to use the same signal gate for the chiff component of a relatively low-pitched tone and for the steady-state component of a relatively high-pitched tone, the present invention employs fewer gating circuits and permits obtaining chiff at more than one footage" in an electronic organ.

SUMMARY OF THE INVENTION In accordance with the present invention, a comparatively simple DC-keyed envelope control circuit provides a steady gating voltage and a chiff pulse of control voltage to two respective identical signal gates. The gates pass respective steady and chiff tones, the latter of substantially shorter duration and higher frequency than the fonner. The gates may be back-to-back diodes controlled by gating voltage applied at their junction or the collector-emitter circuit of a transistor controlled by gating voltage applied at its base. Isolation is provided to prevent control voltage intended for one gate from actuating another gate, the isolation in one embodiment including a transistor base-emitter circuit through which th steady control signal is applied to the gate.

If it is desired to produce more than one footage (i.e. -two or more octavely related tones) upon actuation of a single key, an electronic switch is provided and arranged to be keyed by actuation of key switches for two or more footages. When keyed the electronic switch, which may be a single transistor, causes the steady and chiff control envelopes to be applied to respective signal gates, irrespective of which footage keyed the transistor. A tab-operated footage selector permits selection of the desiredfootage by selectively rendering the key switches in its footage group effective or not in keying the transistor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially block, partially schematic diagram of a prior art chifl' system.

FIG. 2 is a schematic diagram of a single-signal transmission network in accordance with the present invention.

FIG. 2a illustrates a modification of a portion of FIG. 2.

FIG. 3 illustrates graphically the steady state and the chiff components of an organ tone.

F IG. 4 is a schematic diagram of a preferred embodiment of a signal transmission network according to this invention.

FIG. 5 is a schematic circuit diagram of the invention as applied to a system for obtaining diflerent footages.

FIG. 6 is a simplified schematic circuit diagram illustrating the arrangement of the present system as applied to an electronic organ having plural footages, employing diode gates.

FIG. 7 is a schematic circuit diagram of a modification of the system of FIG. 6, employing a transistor gate.

FIG. 8 is a schematic circuit diagram of still a further modification of the system of FIG. 6, employing transistor gates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, representing the system of the aforementioned Brombaugh patent, the dashed-line boxes 2, 4, 6 enclose the elements of signal transmission networks n, (n+29), (n+58),

respectively, of an electronic organ. The network n contains a tone signal source 8, a key switch 10, a keying or envelope control circuit KC a gate 12 and connections between them and corresponds to the lowest-pitched 8' note of a keyboard (not shown) containing the key switch It). Network (n+29), containing tone signal source I4, key switch 16, keying circuit KC, and gate 18 (illustrated in detail), corresponds to a note 29 semitones above that for network n. Also, network (n+58), containing tone signal source 20, key switch 22, keying circuit KC, and gate 24, corresponds to a note 58 semitones above that for network it and 29 semitones above that for network (n+29). The three networks are selected from a gamut thereof covering the nominal pitch range of the instrument. A direct current supply 25 may be connected as shown to the key switches I0, 16, 22. The gate 18, is typical and comprises a pair of diodes 28, 30 (between signal source 14 and a collector 32), a pair of isolating resistors 34, 36 in series between control points A,,, 8,, and a high frequency bypass capacitor 38, all connected as shown in FIG. I. A connection 23 goes from KC, to B, of gate 18, while lead 25 connects KC, with 8,, of gate 24. Further, a common lead 40 connects, as shown, the gate control points, such as B,,, to a variable resistor 42 and direct current supply 44. Tone color or filter circuits TC,, TC,, TC, are connected, respectively between collectors 31, 32, 33 and collector 46, which in turn, is connected via a stoptab switch 48 to an amplifier 50 and loudspeaker 52.

In the operation of the Brombaugh-type system of FIG. I, keying circuits, such as KC, shape the direct current voltage of supply 25, as keyed by switch 16, to render gate 18 operable to pass a signal from tone source 14 to the output system, which signal corresponds to the fundamental or steady-state component of a desired tone. Simultaneously with the described operation, the keying circuit KC, passes shaped direct current via lead 25 to gate 24, which then passes the signal from source 20 via elements TC,, 46, 48 and 50 to speaker 52 for producing a transient or a chiff component of the desired tone. Control of chiff sound level is provided by variable resistor 42. For further details, reference is made to U.S. Pat. No. 3,333,042 to Brombaugh.

Reference is made to FIG. 2 for a signal transmission network according to the present invention. The circuit of FIG. 2 makes use of some of the general circuitry of FIG. 1; similar components are simularly designated. Source 14, for example, is shown connected to gate 18, which comprises two back-toback (anode-to-anode) diodes 28 and 30, their junction or gate control point being indicated as 29. A keyer, K (FIG. 2), corresponds broadly to the keying circuit KC, plus key switch 16 of FIG. 1. The key switch 17 (normally closed) of FIG. 2 is connected betweena common return or ground path 54 and the junction 56 between a pair of series resistors 58, 60. Keyer K further comprises capacitors 62, 64, connected as shown from control point A to ground and to control point B of a gate 24, respectively, not shown but corresponding with gate 24 of FIG. I. The resistor 58 of keyer K may be connected to a direct current supply 26 whose negative terminal is grounded to 54. Associated with gate 18 (FIG. 2) are diode 66, connected cathode to anode between control point 8,, and ground, and resistor 68, connected between control point 8,, and point C of negative direct current supply 70, which may, if desired, be a portion of a common power supply inclusive of source 26.

With regard to the action of the circuit of FIG. 2, in its quiescent state (with key switch 17 closed), capacitor 62 contains no charge of any consequence because point 56 is grounded through switch 17. The same is true for capacitor 64. Also, gate 18 is biased off by the low negative potential provided by supply 70. Thus, no signal from source 14 can pass to the output system. However, upon actuation of the (n+29) key, switch 17 opens and the DC level at control point A starts to rise and is, at the same time transmitted to point 29 of gate 18. As a consequence, gate 18 is gradually rendered conductive to signal from source 14 at a rate determined by the time constant of capacitor 62 in series with resistors 58 and 60, these in parallel with resistor 34. The signal passed by gate 18 is applied to output circuit 72 as the steady-state signal. The potential change at point A is also carried via capacitor 64 to point 13,, of gate 24 corresponding to (n+58), not shown in FIG. 2. The level of the latter point initially rises in sympathy with point A; but soon starts to fall because of the current in the resistors 36 and 68, but which are associated with the (n+58) gate 24 (not shown in FIG. 2). The amplitude of'this chiff envelope control voltage may be controlled by varying the direct current potential at point C. Variable resistor 42, FIG. 2a, in series with resistor 74 and supply 70', which may be substituted for source 70, provide variable voltage control; the switch 76 may be closed to turn off the chiff component.

Diode 66 (FIG. 2) clamps point B at ground and prevents an undue negative potential appearing there quiescently. This allows the chiff control voltage to start positive from about ground potential. When the key for switch 17 is released (closing the switch), the level at point A falls with a time constant, which is determined by resistor 60 in parallel with resistor 34 and capacitor 62, and which is shorter than that for the rise in level of point A This simulates the sound of an organ pipe at the offset of the tone. Because point B of (n+58) gate 24 is clamped by its diode (corresponding to diode 66), no negative excursion appears at this point when switch 17 is closed.

Reference is now made to FIG. 3, wherein the generalized direct current amplitudes at points A,, and 8,, are illustrated versus time. Note that both curves start at the same time t,, and that curve 8,, drops quickly back to zero at time thus simulating the chiff component of an organ tone. A rises to maximum amplitude and remains there until the key for switch 17 is released at t,,, at which time the steady-state component" of the tone decays relatively slowly to zero. Interaction between the potentials at points A and B is negligible, because the level of tone signal at point 29 is relatively low and resistor 36 is relatively high in resistance compared with the impedance of diode 66. Also, at gate 24, interaction between the potentials at points B and A is negligible because of: (1) the low signal level at the input point in gate 24 corresponding to point 29 of gate 18; and (2) the high value of the resistor 34 (in gate 24) relative to resistor 60 (of gate 24).

Another preferred embodiment of this invention appears in 7 FIG. 4, to which reference is now made. Components corresponding to those of FIG. 2 are given the same numerals of reference, but are double primed. For example, 58" of FIG. 4 corresponds to 58 of FIG. 2. For this reason, specific reference will not be made to these components of FIG. 4, as their purpose is the same as in FIG. 2. However, it will be noted that transistor T, corresponds to the switch 17 of FIG. 2, its emitter being connected to common return path 80, its collector being connected to resistors 58" and 60" and its base being connected via resistor 76 and key switch 77 to negative DC supply 25". Also, an additional resistor 78 is connected between the base of T and positive potential 26". Further, the common path 80 is maintained at a low negative level by DC supply 82 to bias gate 18" off in the quiescent mode (i.e. -playing key not depressed).

In operation, normally open key switch 77 allows transistor T, to conduct between collector and emitter, thus maintaining the collector of T at the potential of supply 82 to prevent capacitor 62" from charging. However, when key switch 77 is closed, as by depression of a playing key (not shown), transistor T, is biased off by the negative potential of source 25", and capacitor 62" starts to charge positive. The operation continues in the same manner as the embodiment of F IG. 2. As the key switch 77 opens (by release of its key), T starts conducting again, thus discharging capacitor 26"; the potential at A",,, falls, bringing the steady-state component back to zero.

In order to utilize the embodiment of FIG. 4 to provide more than one footage, reference is now made to FIG. 5, wherein four signal transmission networks n, (n+l2), (ml-29) and (n+4!) are shown. Network n corresponds is for the lowest tone in the 8 foot tone gamut, (n+l2) being for a tone an octave above (4 foot), (n+29) being for chiff for tone n, and (n+4l) being for chifi' for tone (n+12). The signal transmission networks of FIG. 5 are like those of FIG. 4, except that resistor 76 has been replaced by two series-connected resistors 84 and 86 having diode 88 connected from their junction to a common lead 90 connected by 8 foot tab switch 92 to DC supply 82 of 1 volt. The components just described as being additional in FIG. 5 constitute an on-biasing circuit for transistor T, of network "+41 when switch 92 is closed. Similar components perform similar functions for transistors T,, T, and T in networks n, n+l2, and n+29 respectively. Opening of switch 92 disables the on-biasing circuit and lets key switch 93 turn transistor T off, thus sounding tone n+41 Similarly, resistors 94, 96 and diode 98 on-bias transistors T, to T,, when 4 foot tab switch 100 is closed. When switch 100 is opened, closure of key switch 102 applies keying voltage through line 104 and resistors 94, 96 to the base of transistor T, which turns off and allows a 4 foot signal to pass to the output system.

The remaining signal transmission networks of FIG. 5 function in a similar fashion and their description herein would be redundant. Typical values for components are shown for the network (n+41), except for the capacitors which, as a skilled worker in the art would know, have to be scaled from network to network so that lower notes begin and end more slowly than do higher notes and so that bypass capacitors for lower notes are higher in capacitance than those for higher notes. Typical intermediate values are 0.22;; farad for capacitor 62, 0.27 1. farad for capacitor 64 and 0.0022 farad for capacitor 38 (see FIG. 2).

The operation of the present system is now briefly reviewed by reference to FIG. 6 of the accompanying drawings.

Transfer T normally holds point A at l. v. and point B at -1.7 v., since it is a normally closed switch. This condition obtains until S, or S, is opened to select either a 4 or an 8 pitch, and thereafter a key switch, as n36 or n48, is closed. The switches n36, n48 and n60 are normally open. When an appropriate key is depressed and its switch closed, transistor T turns off, allowing the level at point A to rise exponentially, causing a steady tone to build up through gate D, and D,, C, serving as the timing capacitor for the rise. Capacitor C, couples point A to a point B on the 29th gate up the scale (duplicating D D in the gamut of tones, and gates the corresponding tone on transiently. This is the chiff tone, corresponding with the steady tone passing D,, D,. The voltage applied at point P establishes a peak value for the chiff tone signal, and is adjustable. C, and C, are scaled in size, as described above, to produce correct envelope shapes over the range of the keyboard.

The signal level at the junction of diodes D, and D, is small,

while the coupling resistors R, and R are large, (I80 K.) which provides isolation between circuits going back in the gamut 29 steps, at B, and forward 29 steps, via C,.

In the unkeyed state transistor T is on. If 4 foot pitch is selected by opening 8,, T may be turned ofi by operating key n36. If 8 foot pitch is selected by opening 8,, T may be turned off by operating key n48. In either event, when T turns off the level at point A rises with a time constant determined by C, and R, in parallel with R and R in series, to a level determined by R, in series with R and R and the +28 volt supply. The current through R, opens diode gate D D, and allows the fundamental frequency to pass to the output circuit. The remote end of C is connected to point B on the circuit serving the 29th note above the fundamental frequency. Thus point B on the chiff frequency circuit initially rises in sympathy with point A but soon starts to fall because of the current flow through R, and R in the chiff frequency circuit. The amplitude of the chiff envelope appearing at point B in the latter circuit may therefore be controlled by varying the negative potential appearing quiescently at point P.

When the key is released transistor T turns on and the level at point A falls with a time constant, determined by R, in parallel with R, and C which is shorter than the time constant for the level rise at point A. This simulates the action of the organ pipe. Because point B is clamped by D no negative excursion appears at this point when transistor T turns off.

The embodiment of FIG. 6 appears in alternative form in FIG. 7 wherein transistor tone gate T, replaces back-to-back diodes D, and D in each signal transmission network. The normally reverse-biased emitter-base and collector-base junctions of transistor T, are functionally analogous to normally reverse-biased diodes D, and D, of FIG. 6. The tone signal operatively associated with each network is applied to the emitter of T The fundamental control voltage and chiff control voltage are applied to the base of T across high-frequency bypass capacitor C the chiff control voltage being so applied via isolation diode D Operation of the circuits of FIG. 6 and 7 is directly analogous, with T, being rendered conductive and nonconductive in the same manner as diodes D, and D A further modification of the circuit of FIG. 6 is illustrated in FIG. 8 wherein transistor T, once again replaces diodes D, and D In addition, transistor T, is employed in FIG. 8 to replace diodes D and D More particularly, transistor T, has its emitter connected directly to the base of T and its base connected to receive the fundamental or steady-state tone control voltage for each signal transmission network. The collector of T is connected to a source of DC bias potential.

The chiff control voltage for each network is applied via capacitor C, to the junction between the base of T, and emitter of T at which point the chiff bias voltage is applied from terminal P via resistor R Elimination of D, is possible since the collector-emitter circuit of T effectively clamps the base of T when T is turned off and thereby prevents negative excursion at the base of T Elimination of D, is possible since the base-emitter junction of T provides the requisite isolation between the fundamental and chiff control voltage circuits, which isolation is provided by D, in FIG. 7.

The utilization of transistor T. in the manner described and illustrated also permits elimination of the high-frequency bypass capacitor C of FIG. 7. This bypass function is effectively accomplished by the base-emitter circuit of 'I. which presents a high impedance to high-frequency signal components.

Other variations of the circuits illustrated herein are of course possible. For example diodes D, and D, may be replaced by transistors if desired.

Iclaim:

1. In an electronic musical instrument having at least a first and a second tone signal source, an output system and a first and a second gate respectively coupled in series between said sources and said output system, each of said gates comprising at least two back-to-back diodes, the combination comprising: a common return point, a direct current supply having a first section connected between said common return point and a first terminal, a first and a second resistor in series between said first terminal and a first control point in said first gate, a first capacitor between said common return point and said first control point, a keyer switch means connected between said common return point and the junction between said first and second resistors, a third resistor connected between said first control point and the junction between the diodes in said first gate, a fourth resistor connected between a second control point in said second gate and the junction between the diodes of the second gate, a second capacitor between said first and said second control points, a further diode between said common return point and said second control point, and fifth resistor between said second terminal in said direct current supply.

2. The combination according to claim 1, including bypass capacitors between said common return path and the junction between the diodes in said first gate and voltage varying means between said second terminal and said fifth resistor.

3. The combination according to claim 1, wherein said keyer switch means comprises: a sixth resistor, a key switch connected between a third terminal in said direct current supply and said sixth resistor, a transistor circuit coupled between said sixth resistor and the junction between said first resistor and said second resistor, and a seventh resistor between said first terminal and the base of said transistor.

4. In an electronic musical instrument having at least two signal sources corresponding respectively to sources of the fundamental component and the chiff component of a tone, an output system and a pair of gates respectively coupled in series between said sources and said output system, the combination comprising: a common return path, a direct current supply having a first section between a first terminal thereof and said common return path, a first control point, a pair of series resistors between said first terminal and said first control point, a first capacitor between said common return path and said first control point, normally closed switch means between said common return path and the junction between said pair of resistors, a third resistor between said first control point and the junction of diodes in the gate corresponding to the fundamental component of said tone, a second control point, a fourth resistor between the junction of the diodes in the gate connected corresponding with the chiff component of said tone and said second control point, a second capacitor between said first and said second control points, a diode between said common return path and said second control point, and a fifth resistor between said second control point and a second section of said direct current supply of opposite polarity from said first section.

5. The combination according to claim 4, wherein the voltage from said second section of said supply is variable and including capacitive bypass means coupled between the last mentioned of said gates and said common return path.

6. The combination according to claim 4, wherein said common return path is maintained at a direct current voltage of the same polarity but lower in value than said second section of said direct current supply.

7. The combination according to claim 4 wherein said switch means includes a transistor circuit, and

at least one further switch coupled to said transistor circuit.

8. The combination according to claim 7, wherein the voltage from said second section of said supply is variable and including capacitive bypass means coupled between said last mentioned of said gates and said common return path.

9. In an electronic musical instrument the combination comprising:

at least a first, a second and a third signal source, the first source corresponding in frequency to the fundamental component of a first musical tone, the second source corresponding in frequency to the chiff component of said first musical tone and to the fundamental component of a second musical tone, the third source corresponding in frequency to the chiff component of said second musical tone,

an output system,

at least a first, a second and a third gate respectively between said output system and said first, second and third sources,

a direct current supply at least a first, a second and a third keying circuit respectively between said direct current supply and said first, second and third gates at a first control point in each gate, each of said keying circuits comprising:

a first capacitor between said first control point and a first terminal of said direct current supply at a common return path,

a pair of resistors in series between a second terminal of said direct current supply and said first control point,

normally closed switch means between said common return path and the junction between said resistors,

a second capacitor connected at one side to said first control point, the other side of the second capacitor being connected to a second control point in the gate corresponding to the signal source next higher in frequency; there being also:

a first, a second and a third diode respectively between the common return paths of the three keying circuits and the three second control points, and

a third, a fourth and a fifth resistor respectively between second control points and a second terminal of said direct current source opposite in polarity from said first terminal.

10. The combination according to claim 9, including variable voltage means coupled between said second terminal of said direct current supply and said third, fourth and fifth resistors and wherein each of said gates comprises:

a pair of back-to-back diodes and a pair of resistors connected respectively from said first control point and said second control pointto the junction between the diodes.

11. The combination according to claim 9, wherein said switch means includes a transistor circuit and at least one further key switch coupled to the transistor circuit.

12. The combination according to claim 10, wherein said switch means includes a transistor circuit and at least one further key switch coupled to the transistor circuit.

IS. in an electronic organ having a gamut of tone signal sources in a range such that lower-frequency sources correspond respectively to at least the fundamental components of a plurality of musical tones and such that higher frequency sources correspond respectively to at least the chiff components of said plurality of musical tones, an output system and a gamut of gates respectively coupled between said sources and said output system, the combination comprising:

a direct current supply having a first terminal connected to a common return path,

a pair of series resistors connected at one end to a second terminal of said direct current supply a first control point,

a first capacitor between said common return path and the other end of said pair of resistors and said first control point,

normally closed switch means between said common return path and the junction between said resistors,

a third resistor between said first control point and one of said gates coupled to one of said tone signal sources corresponding to the fundamental component of a desired one of said musical tones,

a second capacitor having a first tenninal connected to said first control point,

a fourth resistor between another terminal of said second capacitor and one of said gates coupled to one of said signal sources corresponding to the chiif component of said desired tone,

a diode between said common return path and said second control point,

a fifth resistor between said second control point and a third terminal of said direct current supply having a polarity opposite that of said second terminal thereof.

14. In combination in an electronic organ, a first source of signal corresponding in frequency to the fundamental component of a first musical tone, a second source of signal corresponding in frequency to the chiff component of said first musical tone, a third source of signal corresponding in frequency to the fundamental component of a second musical tone harmonically related to said first musical tone, a fourth source of signal corresponding in frequency to the chiff component of said second musical tone, an output system, four gate means coupled respectively between said signal sources and said output system, said gate means each having a first control point and a second control point, a common return path, a direct current supply having a first terminal connected to said common return path, three key switch means connected to a second terminal of said direct current source,

three keying means, the first of which between one of said key 5 switch means and the first control point of one of said gate means, the second and third of which are each respectively between two difierent ones of said key switch means and the second control points of two of said gate means, at least three transistor on-biasing circuits coupled to said at least three keying circuit means, and first circuit means connected to said onbiasing circuits for disablement thereof, whereby said key switches and said keying circuits can actuate said gate means to produce said first musical tone, at least two additional onbiasing circuits respectively coupled to two of said at least three keying circuit means, and second circuit means connected to said additional on-biasing circuits for disablement thereof whereby certain of said key switch means and said keying circuit means can actuate certain of said gate means to produce said second musical tone.

15. The combination according to claim 14, wherein said three on-biasing circuits comprise:

a first pair of resistors in series between one of said key switch means and one of said keying circuit means, a diode connected between said first circuit means and the junction between said first pair of resistors; and wherein said additional on-biasing circuits each comprises, a second pair of resistors in series between one of said key switch means and one of said two of said at least three keying circuit means, a diode connected between said second circuit means and the junction between said second pair of resistors; and wherein said three keying circuit means each comprises a third pair of resistors connected between a third terminal of said direct current supply and the first control point of its associated gate means, a first capacitor between said first control point and the second control point of its associated gate means, and a transistor connected between one of said first pair of resistors and the junction between said third pair of resistors.

16. The combination according to claim 14, wherein each of said gates comprises:

a pair of back-to-back diodes between said output system and the source to which the gate is coupled,

a first pair of resistors between the junction of said diodes and the first and second control points, respectively; and wherein there is included at least three chiff control circuits respectively connected to at least three of said gates, said chiff control circuits each comprising a diode between the second control point of the gate to which the chiff control circuit is connected and the corresponding one of said keying circuits, and

a third resistor between the last-mentioned control point and a third terminal of said direct current supply.

17. In an electronic musical instrument having a first tone signal source corresponding to the steady-state component of a musical tone, a second tone signal source corresponding to a transient component of said musical tone, a direct current 60 supply and an output system, the combination comprising:

a pair of back-to-back diodes connected in series between said first tone signal source and said output system,

a first pair of series resistors,

a key switch connected between said direct current supply and one end of said first pair of resistors, a first control point,

a second pair of series resistors connected between said direct current supply and said first control point,

a transistor having a base connected to the other end of said first pair of resistors, an emitter connected to said direct current supply and a collector connected to the junction between said second pair of resistors, said collector being connected to said direct current supply,

7 a fifth resistor connected between said direct current supply and said base,

a selector switch connected at one pole to said direct current supply,

a third diode connected between the other pole of said selector switch and the junction between said first pair of resistors,

a first capacitor connected between said first control point and said emitter,

a sixth resistor connected between the said first control point and the junction between said back-to-back diodes, a second control point,

said seventh resistor connected between a second control point and said junction between said back-to-back diodes,

an eighth resistor connected between said second control point and said direct current supply, and

circuit means connected between said second signal source and said second control point for supplying said transient component.

18. A double-utility gating system for gating both chifl and steady tone signals to a load, comprising:

a gate having a signal input terminal, a signal output terminal connected to said load, and a gating terminal,

a normally closed switch,

means responsive to opening said switch for applying a gating current to said gating terminal, said gate being arranged to be conductive of said tone signal when supplied with said gating current,

an isolating resistance of at least l00.l( connected between said switch and said gating terminal,

a further isolating resistance of at least l00.K connected to said gating terminal,

means including a series capacitor for applying a chiff current impulse to said gating terminal via said further isolating resistance,

a timing capacitor connected across said switch, and

a source of voltage and current limiting resistance connected in series with each other and with said switch, said gate being arranged to operate in its linear region in terms of the amplitude of said tone signal and the amplitudes of gating currents.

19. The combination according to claim 18, wherein said gate is a double-diode gate, the diodes of said doublediode gate being poled identically with respect to said gating terminal.

20. The combination according to claim 18, wherein is further provided means for applying a steady DC off-gating voltage to said gating terminal having a value selected to adjust the chiff current peak to a selected value.

21. The combination according to claim 20, wherein said switch is a transistor switch, and wherein two footage selection switches are each arranged to selectively maintain said transistor switch open or closed.

22. The combination according to claim 21, wherein are provided normally open key switches each connected to render said transistor switch open when the key switch is closed.

23. The combination according to claim 21, wherein said switch means includes a transistor circuit, and

at least one further key switch coupled to said transistor circuit.

24. in an electronic organ having provision for chiff tones, a gamut of tone signal sources, a separate and different single gate connected in cascade with each of said tone signal sources on a one for one basis, each of said gates having a gating point, a normally closed gate control switch associated with each gate and normally connecting the gating point of that gate to a lead at a fixed reference potential, said potential being selected to maintain said gates normally nonconductive, when applied to the gating points of the gates, a normally open key switch actuable to close condition on depression of a key of said organ, means responsive to said key switch when closed for applying a steady gating signal to one of said gates and for directing a transient pulse to chiff gating signal to a further one of said gates, a lead for applying chifi' gating signal to said one of said gates from another one of said gates, and means for electrically isolating said further one of said gates from said one of said gates and from said another one of said gates.

25. The combination according to claim 24 wherein said single gate comprises a pair of diodes having like electrodes connected to said gating point, the opposite electrode of one of said diodes being connected to a tone signal source, the opposite electrode of the other of said diodes being connected in common with all of said single gates to a load.

26. The combination according to claim 24 wherein said single gate comprises a transistor having a base electrode corresponding to said gating point, an emitter electrode connected to a tone signal source, and a collector electrode connected to a load.

27. The combination according to claim 24 wherein said means for electrically isolating comprises a transistor having its emitter connected to said gating point, said chifl' gating signal from said another one of said gates also being applied to said gating point, and wherein said steady gating signal is applied to the base of said transistor.

28. A gating circuit, comprising a source of voltage, a capacitor, resistance connecting said source of voltage and said capacitor in a series circuit, a normally closed switch connected between a top of said resistance located intermediate the ends of said resistance and a common terminal of said capacitor and said source of voltage, whereby said capacitor is normally uncharged by said source of voltage and said capacitor is charged from said source of voltage via said resistance when said switch is open and said capacitor discharges via said top and said switch when said switch is reclosed, a normally open gate having a first control point, a source of tone signal, a load, means connecting said source of tone signal to said load via said gate, and means connecting said capacitor to said control point, said source of voltage being poled to close said gate.

29. The combination according to claim 28, wherein is provided a further gate having a further control point, a capacitive connection between said control point and said further control point.

30. The combination according to claim 28, wherein said switch is a transistor having its emitter-collector electrodes connected across said capacitor, means normally maintaining said transistor fully conductive, a normally open key switch, and means responsive to closure of said key switch for rendering said transistor nonconductive.

31. The combination according to claim 28, wherein is provided an isolating resistance connected between said capacitor and said control point, means including a capacitive connection to said control point and a further isolating resistance connected between said capacitive connection and said control point, a further key and means applying voltage to said control point via said further isolating resistance and said capacitive connection in response to actuation of said further key.

32. The combination according to claim 31, wherein said switch is a transistor, having its emitter-collector electrodes connected across said capacitor, means normally maintaining said transistor fully conductive a normally open key switch, and means responsive to closure of said key switch for rendering said transistor nonconductive.

* II I i i 

1. In an electronic musical instrument having at least a first and a second tone signal source, an output system and a first and a second gate respectively coupled in series between said sources and said output system, each of said gates comprising at least two back-to-back diodes, the combination comprising: a common return point, a direct current supply having a first section connected between said common return point and a first terminal, a first and a second resistor in series between said first terminal and a first control point in said first gate, a first capacitor between said common return point and said first control point, a keyer switch means connected between said common return point and the junction between said first and second resistors, a third resistor connected between said first control point and the junction between the diodes in said first gate, a fourth resistor connected between a second control point in said second gate and the junction between the diodes of the second gate, a second capacitor between said first and said second control points, a further diode between said common return point and said second control point, and fifth resistor between said second terminal in said direct current supply.
 2. The combination according to claim 1, including bypass capacitors between said common return path and the junction between the diodes in said first gate and voltage vArying means between said second terminal and said fifth resistor.
 3. The combination according to claim 1, wherein said keyer switch means comprises: a sixth resistor, a key switch connected between a third terminal in said direct current supply and said sixth resistor, a transistor circuit coupled between said sixth resistor and the junction between said first resistor and said second resistor, and a seventh resistor between said first terminal and the base of said transistor.
 4. In an electronic musical instrument having at least two signal sources corresponding respectively to sources of the fundamental component and the chiff component of a tone, an output system and a pair of gates respectively coupled in series between said sources and said output system, the combination comprising: a common return path, a direct current supply having a first section between a first terminal thereof and said common return path, a first control point, a pair of series resistors between said first terminal and said first control point, a first capacitor between said common return path and said first control point, normally closed switch means between said common return path and the junction between said pair of resistors, a third resistor between said first control point and the junction of diodes in the gate corresponding to the fundamental component of said tone, a second control point, a fourth resistor between the junction of the diodes in the gate connected corresponding with the chiff component of said tone and said second control point, a second capacitor between said first and said second control points, a diode between said common return path and said second control point, and a fifth resistor between said second control point and a second section of said direct current supply of opposite polarity from said first section.
 5. The combination according to claim 4, wherein the voltage from said second section of said supply is variable and including capacitive bypass means coupled between the last mentioned of said gates and said common return path.
 6. The combination according to claim 4, wherein said common return path is maintained at a direct current voltage of the same polarity but lower in value than said second section of said direct current supply.
 7. The combination according to claim 4 wherein said switch means includes a transistor circuit, and at least one further switch coupled to said transistor circuit.
 8. The combination according to claim 7, wherein the voltage from said second section of said supply is variable and including capacitive bypass means coupled between said last mentioned of said gates and said common return path.
 9. In an electronic musical instrument the combination comprising: at least a first, a second and a third signal source, the first source corresponding in frequency to the fundamental component of a first musical tone, the second source corresponding in frequency to the chiff component of said first musical tone and to the fundamental component of a second musical tone, the third source corresponding in frequency to the chiff component of said second musical tone, an output system, at least a first, a second and a third gate respectively between said output system and said first, second and third sources, a direct current supply at least a first, a second and a third keying circuit respectively between said direct current supply and said first, second and third gates at a first control point in each gate, each of said keying circuits comprising: a first capacitor between said first control point and a first terminal of said direct current supply at a common return path, a pair of resistors in series between a second terminal of said direct current supply and said first control point, normally closed switch means between said common return path and the junction between said resistors, a second capacitor connected at one side to said first control point, the othEr side of the second capacitor being connected to a second control point in the gate corresponding to the signal source next higher in frequency; there being also: a first, a second and a third diode respectively between the common return paths of the three keying circuits and the three second control points, and a third, a fourth and a fifth resistor respectively between second control points and a second terminal of said direct current source opposite in polarity from said first terminal.
 10. The combination according to claim 9, including variable voltage means coupled between said second terminal of said direct current supply and said third, fourth and fifth resistors and wherein each of said gates comprises: a pair of back-to-back diodes and a pair of resistors connected respectively from said first control point and said second control point to the junction between the diodes.
 11. The combination according to claim 9, wherein said switch means includes a transistor circuit and at least one further key switch coupled to the transistor circuit.
 12. The combination according to claim 10, wherein said switch means includes a transistor circuit and at least one further key switch coupled to the transistor circuit.
 13. In an electronic organ having a gamut of tone signal sources in a range such that lower-frequency sources correspond respectively to at least the fundamental components of a plurality of musical tones and such that higher frequency sources correspond respectively to at least the chiff components of said plurality of musical tones, an output system and a gamut of gates respectively coupled between said sources and said output system, the combination comprising: a direct current supply having a first terminal connected to a common return path, a pair of series resistors connected at one end to a second terminal of said direct current supply a first control point, a first capacitor between said common return path and the other end of said pair of resistors and said first control point, normally closed switch means between said common return path and the junction between said resistors, a third resistor between said first control point and one of said gates coupled to one of said tone signal sources corresponding to the fundamental component of a desired one of said musical tones, a second capacitor having a first terminal connected to said first control point, a fourth resistor between another terminal of said second capacitor and one of said gates coupled to one of said signal sources corresponding to the chiff component of said desired tone, a diode between said common return path and said second control point, a fifth resistor between said second control point and a third terminal of said direct current supply having a polarity opposite that of said second terminal thereof.
 14. In combination in an electronic organ, a first source of signal corresponding in frequency to the fundamental component of a first musical tone, a second source of signal corresponding in frequency to the chiff component of said first musical tone, a third source of signal corresponding in frequency to the fundamental component of a second musical tone harmonically related to said first musical tone, a fourth source of signal corresponding in frequency to the chiff component of said second musical tone, an output system, four gate means coupled respectively between said signal sources and said output system, said gate means each having a first control point and a second control point, a common return path, a direct current supply having a first terminal connected to said common return path, three key switch means connected to a second terminal of said direct current source, three keying circuit means, the first of which between one of said key switch means and the first control point of one of said gate means, the second and third of which are each respectively between two different ones of said key switch means and the second control points of two of said gate means, at least three transistor on-biasing circuits coupled to said at least three keying circuit means, and first circuit means connected to said on-biasing circuits for disablement thereof, whereby said key switches and said keying circuits can actuate said gate means to produce said first musical tone, at least two additional on-biasing circuits respectively coupled to two of said at least three keying circuit means, and second circuit means connected to said additional on-biasing circuits for disablement thereof whereby certain of said key switch means and said keying circuit means can actuate certain of said gate means to produce said second musical tone.
 15. The combination according to claim 14, wherein said three on-biasing circuits comprise: a first pair of resistors in series between one of said key switch means and one of said keying circuit means, a diode connected between said first circuit means and the junction between said first pair of resistors; and wherein said additional on-biasing circuits each comprises, a second pair of resistors in series between one of said key switch means and one of said two of said at least three keying circuit means, a diode connected between said second circuit means and the junction between said second pair of resistors; and wherein said three keying circuit means each comprises a third pair of resistors connected between a third terminal of said direct current supply and the first control point of its associated gate means, a first capacitor between said first control point and the second control point of its associated gate means, and a transistor connected between one of said first pair of resistors and the junction between said third pair of resistors.
 16. The combination according to claim 14, wherein each of said gates comprises: a pair of back-to-back diodes between said output system and the source to which the gate is coupled, a first pair of resistors between the junction of said diodes and the first and second control points, respectively; and wherein there is included at least three chiff control circuits respectively connected to at least three of said gates, said chiff control circuits each comprising a diode between the second control point of the gate to which the chiff control circuit is connected and the corresponding one of said keying circuits, and a third resistor between the last-mentioned control point and a third terminal of said direct current supply.
 17. In an electronic musical instrument having a first tone signal source corresponding to the steady-state component of a musical tone, a second tone signal source corresponding to a transient component of said musical tone, a direct current supply and an output system, the combination comprising: a pair of back-to-back diodes connected in series between said first tone signal source and said output system, a first pair of series resistors, a key switch connected between said direct current supply and one end of said first pair of resistors, a first control point, a second pair of series resistors connected between said direct current supply and said first control point, a transistor having a base connected to the other end of said first pair of resistors, an emitter connected to said direct current supply and a collector connected to the junction between said second pair of resistors, said collector being connected to said direct current supply, a fifth resistor connected between said direct current supply and said base, a selector switch connected at one pole to said direct current supply, a third diode connected between the other pole of said selector switch and the junction between said first pair of resistors, a first capacitor connected between said first control point and said emitter, a sixth resistor connected between the said first control point and the junCtion between said back-to-back diodes, a second control point, said seventh resistor connected between a second control point and said junction between said back-to-back diodes, an eighth resistor connected between said second control point and said direct current supply, and circuit means connected between said second signal source and said second control point for supplying said transient component.
 18. A double-utility gating system for gating both chiff and steady tone signals to a load, comprising: a gate having a signal input terminal, a signal output terminal connected to said load, and a gating terminal, a normally closed switch, means responsive to opening said switch for applying a gating current to said gating terminal, said gate being arranged to be conductive of said tone signal when supplied with said gating current, an isolating resistance of at least 100.K connected between said switch and said gating terminal, a further isolating resistance of at least 100.K connected to said gating terminal, means including a series capacitor for applying a chiff current impulse to said gating terminal via said further isolating resistance, a timing capacitor connected across said switch, and a source of voltage and current limiting resistance connected in series with each other and with said switch, said gate being arranged to operate in its linear region in terms of the amplitude of said tone signal and the amplitudes of gating currents.
 19. The combination according to claim 18, wherein said gate is a double-diode gate, the diodes of said double-diode gate being poled identically with respect to said gating terminal.
 20. The combination according to claim 18, wherein is further provided means for applying a steady DC off-gating voltage to said gating terminal having a value selected to adjust the chiff current peak to a selected value.
 21. The combination according to claim 20, wherein said switch is a transistor switch, and wherein two footage selection switches are each arranged to selectively maintain said transistor switch open or closed.
 22. The combination according to claim 21, wherein are provided normally open key switches each connected to render said transistor switch open when the key switch is closed.
 23. The combination according to claim 21, wherein said switch means includes a transistor circuit, and at least one further key switch coupled to said transistor circuit.
 24. In an electronic organ having provision for chiff tones, a gamut of tone signal sources, a separate and different single gate connected in cascade with each of said tone signal sources on a one for one basis, each of said gates having a gating point, a normally closed gate control switch associated with each gate and normally connecting the gating point of that gate to a lead at a fixed reference potential, said potential being selected to maintain said gates normally nonconductive, when applied to the gating points of the gates, a normally open key switch actuable to close condition on depression of a key of said organ, means responsive to said key switch when closed for applying a steady gating signal to one of said gates and for directing a transient pulse to chiff gating signal to a further one of said gates, a lead for applying chiff gating signal to said one of said gates from another one of said gates, and means for electrically isolating said further one of said gates from said one of said gates and from said another one of said gates.
 25. The combination according to claim 24 wherein said single gate comprises a pair of diodes having like electrodes connected to said gating point, the opposite electrode of one of said diodes being connected to a tone signal source, the opposite electrode of the other of said diodes being connected in common with all of said single gates to a load.
 26. The combination according to claim 24 wherein said single gate comprises A transistor having a base electrode corresponding to said gating point, an emitter electrode connected to a tone signal source, and a collector electrode connected to a load.
 27. The combination according to claim 24 wherein said means for electrically isolating comprises a transistor having its emitter connected to said gating point, said chiff gating signal from said another one of said gates also being applied to said gating point, and wherein said steady gating signal is applied to the base of said transistor.
 28. A gating circuit, comprising a source of voltage, a capacitor, resistance connecting said source of voltage and said capacitor in a series circuit, a normally closed switch connected between a top of said resistance located intermediate the ends of said resistance and a common terminal of said capacitor and said source of voltage, whereby said capacitor is normally uncharged by said source of voltage and said capacitor is charged from said source of voltage via said resistance when said switch is open and said capacitor discharges via said top and said switch when said switch is reclosed, a normally open gate having a first control point, a source of tone signal, a load, means connecting said source of tone signal to said load via said gate, and means connecting said capacitor to said control point, said source of voltage being poled to close said gate.
 29. The combination according to claim 28, wherein is provided a further gate having a further control point, a capacitive connection between said control point and said further control point.
 30. The combination according to claim 28, wherein said switch is a transistor having its emitter-collector electrodes connected across said capacitor, means normally maintaining said transistor fully conductive, a normally open key switch, and means responsive to closure of said key switch for rendering said transistor nonconductive.
 31. The combination according to claim 28, wherein is provided an isolating resistance connected between said capacitor and said control point, means including a capacitive connection to said control point and a further isolating resistance connected between said capacitive connection and said control point, a further key and means applying voltage to said control point via said further isolating resistance and said capacitive connection in response to actuation of said further key.
 32. The combination according to claim 31, wherein said switch is a transistor, having its emitter-collector electrodes connected across said capacitor, means normally maintaining said transistor fully conductive, a normally open key switch, and means responsive to closure of said key switch for rendering said transistor nonconductive. 